How to: Disable macOS System Integrity Protection
If you are running OS X El Capitan, macOS Sierra or macOS Mojave you will need to disable System Integrity Protection to modify system files and directories.
To disable System Integrity Protection, boot into recovery mode by restarting and then holding
⌘R as you hear the startup chime. Then start the Terminal from the Utilities menu.
Run the following command
$ csrutil disable
Then reboot. You are good to go.
If you wish to turn it back on, follow the instructions above but instead use:
$ csrutil enable